Method and apparatus for making a hooked pile fabric



K. FRST v METHOD AND APPARATUS FOR lV'AI/{INGER 1 A HOOKED PILE FABR Jan. '21, 1958v Filed Oct. 25, 1955 s. n A

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United Bates Patent O METHOD AND APPARATUS FOR MAKING A HOOKED PILE FABRIC Karl Frster, Munich, Germany Application October 25, 1955, Serial No. 542,620

Claims priority, application Germany October 26, 1954 6 Claims. (Cl. 26-2) The invention relates to a method and apparatus for producing fabrics which can adhere to each other by interengaging very small fiber hooks.

Fabrics provided with hook-shaped upright threads are known. Such fabrics are velvet type or pile fabrics containing in closely spaced relationship raised pile threads projecting from the foundation structure. Said raised pile threads consist of synthetic thermoplastic resin material, and the terminal portions of said threads have been bent to hooks by application of heat.

The hook shape of said raised pile threads was produced by passing the same around heated transverse bars and cutting the obtained loops, so that the thermoplastic threads subjected to the heat assumed and retained the desired shape. After the loops had been cut, they formed the raised pile threads with hook-shaped ends, which were arranged substantially parallel to each other over the whole surface of the fabric.

A drawback of these known fabrics is due to the fact that the strength of the adhesion between two superposed pieces of fabric depends essentially on the angle which the weft or warp threads of the superposed fabrics form with each other. The maximum adhesion is obtained when the weft or warp, respectively, of the superposed fabrics form a right angle with each other; in said position, the largest number of the hooks will grip each other. If, however, the fabrics are superposed in a position Where the planes of the hooks are parallel to each other, only sporadic interengagement takes place, and the adhesion is correspondingly smaller. In addition, the manufacture of such fabrics requires specific arrangements at the loom.

lt is a principal object of the invention to provide a method for producing fabrics of the character described, which do not show the recited drawbacks and can be obtained from any starting material, irrespective of the kind of loom on which the material had been made.

Another object of the invention is to provide an apparatus for bending the ends of thermoplastic pile threads at random directions.

Other objects and advantages will be apparent from a consideration of the specification and claims.

In accordance with the invention, the ends of thermoplastic raised pile threads are heated, so as to become plastic and deformable, and are simultaneously subjected to axial pressure by means of a faceted pressure roller, whereby they are bent to hooks. The facets are preferably semi-spherical and concave and have a radius corresponding to the desired radius of the hooks formed by bending of the pile threads. The bending to the hooks takes place in all possible directions. With respect to said directions, the distribution of the hooks is such that irrespective of the position taken up by two superposed fabrics, always optimum adhesion is obtained because in view of the statistic distribution a substantially equal number of hooks can interengage in whatever position.

Any type of pile fabric may be used as starting material. It is not necessary to use fabrics in which the pile has been formed by cutting the loops; it is, for instance,

2,820,277 Patented Jan. 21, 1958 ice also possible to interweave the warp threads of two parallel foundation fabrics and to produce the pile by cutting the two foundation fabrics in the symmetry plane.

In order to prevent pulling out of the hooked pile threads from the foundation fabric, the latter should be woven as tightly as possible. It is of advantage to cement the bases of the individual thermoplastic pile threads together and/or to the foundation fabric, either by a suitable thermal or chemical treatment applied to the foundation fabric. Such treatment may be applied prior to, or after formation of the hooks.

The novel features of the invention will be better understood from the following description taken in connection with the accompanying drawings, in which a suitable apparatus for preparing the fabric has been shown for purpose of illustration.

In the drawing:

Fig. 1 represents a vertical section of the entire apparatus;

Fig. 2 is a partial sectional view, on an enlarged scale, of the roll rolling on the web of the pile fabric, and

Fig. 3 is a partial view of the surface of the roll.

As shown in Fig. 1, a pile fabric 1, in which the pile threads are already cut, is pulled by a suitable mechanism (not shown) at a constant speed in direction of arrow 2 over a slideway 3, whereby the pile is on that face of the fabric which is not gliding on the slide-way. Above the slide-way 3, a roll 4 is rotatably arranged in such a way that the distance of the roller surface from the support 3 is adjustable.

The roll 4 is driven in direction of the arrow 5 at a speed corresponding to the speed at which the fabric is passed over the slide-way 3. The surfaceof the roll 4 is honeycombed by semispherical concave facets 6, which have a diameter corresponding to the diameter of the hooks to be formed, for instance about 0.25 mm. The roll 4 is heated and maintained at a predetermined temperature by means of a thermostat. When perlon pile threads are used, the temperature of the roll surface should be about ISO- C.

The slide-way 3 is provided with cooling means for the foundation fabric and the lower portion of the upright pile threads. If air cooling is used, the slide-way 3 may contain slots 7, through which cooling air passes from the cooling space 8 against the lower face of the fabric 1 traveling over the slideway 3. Said cooled air, which is admitted under pressure, passes through the porous foundation of the fabric 1 and is sucked off by means of aspirators 10 through the funnels 9.

The production of the hooks by means of the described apparatus is as follows:

The fabric, with projecting upright pile threads 11, is drawn below the roll 4 on the slide-way 3. Hereby, the tips 12 of the threads 11 strike against the facets 6 and are plasticized by the contact with the hot surface of the roll. The lower ends of the threads 11 retain their rigidity and elasticity because they are cooled by the air forced through the slots 7 of the slide-way 3.

On the further passage between roll and slide-way, the threads 11 are subjected to axial pressure, whereby the tips 12 are bent conforming to the shape of the facets 6, and from hooks. The direction in which the hooks are formed depends on the deflection of the pile tips by the impact with the facets, and is produced according to the laws of statistics in every possible way.

As soon as the web 1 has passed below the lowest longitudinal surface line of the roll 4, that is, after the tips 12 have been bent to hooks 13 and are beneath the axis of the roll 4, the deforming procedure is terminated. As the tips have been plasticized by the heat, the shape of the hooks is retained (Fig. 2).

Towards the exit side of the apparatus, the cooling 'slots 7 irelenlaigd, `s^o that the cooling effect extends `now ltoth'ebenthooks "13 and sets the sax'ne in"their hooked shape. The bending angle of the obtained hooks ifs Aa function of the V,distance,lpetween the roll 4 and the slideway and can-'be,adjusted by `s`fuitabl`e adjustment 'of said distance.

A"Theirnetho'd of th'ejinv'e'ntion kis 'preferably`y applied `to bands, `which :subsequentlyfrnay be sewn 'orfbonded to the 'materials' to be united. Such adhesive fastening bands can beszedinfrna'ny Ways., `for 'instai:ice attach'edto garments, "pockets, andw'th'eY like. They are 'ilexible and do not scratch, -Vare washable gland vcan ibe `'produced in any shade or :also in "variegated'de'sg'ns ccrdingtotlie intended application, the 'strength' of the pile threads,l the height of the pile, the radiuslnd bending Va'ngle `ffthe hooks, :as Well' as theirfnlifnbe'r per unit of surfacec'an be For rougliened Wo'ol fabrics,it is vsuficient'to press such Vanadhesive'band' against lthe surface f the ,'w'ool fabric p employed, and inf the; stepsff''illofwe'd, :without: `departing vfrom the spiritand scope dftheihvention as' diine'd 'in the appended claims.

'I claim:

1.,'Av method 'of inakingahooked'pile'fabric suitable as fastening means, comprising providing a foundation "abric'hvirig a "plurality of upright thermoplastic pile threads of substantially equal length, passing said fabric under a roll bending the tips of said pile threads in random directions to hooks, heating said tips during said passage to a plastic deformable state and simultaneously cooling the lower ends of said pile threads, and subseque'ntly setting the 4-b'enttipsof `the-pile threadsl in said hook shape.

2. A method as delinedvinv claim'l, including the step of bonding the lower ends of said pile-threads to the foundationA fabric.

3. A method as defined in claim 1, whereinsaid pile threads 'are`superpolyar'nides, and wherein the said roll is heated to a surfacetemper'atureof about ISO-190 C.

4. A device for making a hooked pile fabric comprising a stationary support for a traveling fabric having a plurality of upright=thermoplasticpile threads,and a heated roll provided with azsurface honeycombed with semispherical concave facets,said roll when in operative en- .ggagement with saidfpile-threadsbending the tipsof said threads to-fhooks'formingrandom angles with the plane l normal to the surface' of said fabric.

@5.A1device -as;denedin claim 4, cornprisingslots in saidsupport;for--admissionlofl acooling agent to said f traveling fabric.

6. A device asdeiined in claim 5 wherein the width of References "Citedin the le of vthis patent UNITED STATES PATENTS Holland DCC. l, Mestral. Sept. 13, 1955 

